Genetic background and production periods shape the microRNA profiles of the gut in laying hens.

There is growing evidence of the importance of miRNAs for intestinal functional properties and nutritional uptake. Comparative miRNAs profiles of the jejunal mucosa were established against two genetic backgrounds (Lohmann Brown-Classic (LB) and Lohmann LSL-Classic (LSL), which are similar in egg production but differ in physiological traits including mineral utilization, along the production periods of laying hens. The target genes of miRNAs higher expressed in LB vs. LSL (miR-126-3p, miR-214, miR-24-3p, miR-726-5p, miR-29b-3p) were enriched for energy pathways at all stages. The target genes of the miRNAs higher in LSL (miR-1788-5p, miR-103-3p, miR-22-5p, miR-221-3p, miR-375) were more enriched for immune and the bone signalling pathways. The most prominent expression differences were between 16 and 24 weeks of age before and after onset of laying. Our results evidence central roles of intestinal miRNAs as regulators of gene expression, influencing intestinal homeostasis and adaptation to environment in different strains and production phases.